1. Field of the Invention
This invention relates generally to pressure regulators and more particularly to an improved pressure regulator utilizing a diaphragm.
2. Description of the Art
In the field of pressure regulators, it is known to utilize a plunger-type valve which includes radial seals (sliding seals) in the operation of the pressure regulator. Such a typical pressure regulator having sliding seals is illustrated in FIG. 8. One problem with such regulators is that when used in applications in which the fluid flowing through the regulator contains a high degree of particulate matter, for example, machine tool coolant, these regulators are prone to reduced valve life and poor operation. In particular, the suspended particles in the fluid wear on the sliding seals causing damage to the seals and subsequent leakage of fluid which then can contaminate other moving parts of the regulator as well as causing a loss of pressure. The contamination of the sliding seals due to the particulates in the fluid results in reduced regulator valve life and poor operating efficiency.
A different type of pressure regulator such as shown in U.S. Pat. No. 5,107,887, utilizes dual flexible diaphragms connected to the valve with sealing members positioned at the various points of connection of the diaphragm to the valve stem and regulator body. A problem with such regulators utilizing a diaphragm is that the flexible diaphragm has a tendency when under pressure to accumulate a significant portion of diaphragm material in the area between the valve stem and regulator body. This results in a thinner or reduced portion of diaphragm material at the hinge or connection positions of the valve stem and regulator body. The formation of increased portions of diaphragm material or xe2x80x9cconvolutexe2x80x9d in the unclamped area results in thinning or xe2x80x9cneckingxe2x80x9d of diaphragm material at the hinge positions and leads to reduced operational life of the diaphragm. This is especially apparent when the pressure regulator is used in applications requiring a high number of cycles of the valve. In these high cycle applications, the formation of a convolute in the unclamped area of the diaphragm significantly decreases the operational life of the valve, and inhibits the valve""s ability to respond rapidly in a high speed cyclic application.
What is needed is a pressure regulator which provides consistent pressure regulation with improved regulator valve life and with improved operating efficiency. What is further needed is a pressure regulator apparatus capable of operating in an environment in which the pumping fluid contains a significant degree of particulates without reducing the regulator valve life. Such a pressure regulator should further be able to operate in a high speed cyclic application with improved regulator valve life while also protecting moving parts of the regulator from chemical or mechanically abrasive exposure of the pumped fluids.
The present invention provides a pressure regulator apparatus which demonstrates consistent pressure regulation with improved regulator valve life and with improved operating efficiency. Further, the pressure regulator apparatus provides for improved regulator valve life while operating in a high cycle application or in an environment in which the pumped fluid contains a high degree of particulates.
According to one aspect of the present invention, there is provided a pressure regulator apparatus which includes a regulator body having an inlet, an outlet and a passage communicating there between. The pressure regulator apparatus includes a valve disposed within the passage having a valve seat and a valve stem with one end of the valve stem biased toward the valve seat. The pressure regulator apparatus further includes a plunger member connected to the valve stem at an end opposite the valve seat with the plunger member movable axially with respect to the valve seat. The plunger member is further connected to a biasing member so that the plunger member biases the valve stem toward the valve seat to control the pressure of the fluid flowing through the pressure regulator. A flexible diaphragm is connected at an inner end between the valve stem and plunger member and connected at an outer end against the regulator body. The diaphragm is flexible as the plunger member and valve stem move axially with respect to the valve seat. Sealing members are disposed within a channel or groove in the valve stem and regulator body for engagement with the diaphragm to seal the passage of the regulator body. The cross-sectional area of the sealing members is less than the cross-sectional area of the channel in which the sealing members are disposed so that a portion of the diaphragm may extend into the channel when the diaphragm is under pressure to reduce movement of the diaphragm into the area between the regulator body and valve. According to one embodiment of the present invention, the sealing members comprise O-ring seals. In a preferred embodiment, the cross-sectional area of the O-ring seals are approximately 80-90 percent of the cross-sectional area of the channels in which the O-ring seals are disposed.
Pursuant to another embodiment of the invention, the diaphragm is compressed between the plunger member and the valve stem in sufficient amount to retain the diaphragm in position and prevent leakage between the diaphragm and sealing member while minimizing the movement of diaphragm material into the non-compressed area between the valve and regulator body. In one embodiment, the plunger member is secured to the valve stem such that the diaphragm is subject to between approximately 5-20 percent compression at the inner end of the diaphragm between the valve stem and plunger member. In a preferred embodiment, the diaphragm is subject to approximately 8-15 percent compression. Similarly, the outer end of the diaphragm is compressed between the regulator body and the diaphragm cover in sufficient amount to retain the diaphragm in position and prevent leakage between the diaphragm and sealing member while minimizing movement of the diaphragm into the non-compressed area between the valve and regulator body. In one embodiment, the diaphragm cover is secured against the regulator body such that the diaphragm is subject to between approximately 5-20 percent compression at the outer end of the diaphragm between the regulator body and diaphragm cover. In a preferred embodiment, the outer end of the diaphragm is subject to approximately 8-15 percent compression. Preferably, the connection of the diaphragm cover to the regulator body forms a cavity adjacent the outer end of the diaphragm such that upon compression of the diaphragm when the diaphragm cover is secured against the regulator body, a portion of the compressed diaphragm may move into the cavity adjacent the outer end of the diaphragm.
In accordance with another embodiment of the invention, the plunger member is disposed within the diaphragm cover for slidable movement therein. The plunger member preferably includes a self-sacrificial lubricating element, such as Teflon. The lubricating element is disposed within a groove formed on an outer surface of the plunger member such that the lubricating element contacts an adjacent surface of the diaphragm cover to provide lubrication between the plunger member and diaphragm cover. In a preferred embodiment, a plurality of lubricating elements are disposed in a plurality of grooves in the outer surface of the plunger member.
The above-described features and advantages, along with various other advantages and features of novelty, are pointed out with particularity in the claims of the present application which form a part hereof. However, for a better understanding of the invention, its advantages, and objects obtained by its use, reference should be made to the drawings which form a further part of the present application and to the accompanying descriptive matter in which there is illustrated and described preferred embodiments of the invention.